Illumination is used to light objects for seeing, as also for photography, microscopy, scientific purposes, entertainment productions (including theater, television and movies), projection of images and as backlights of displays. Backlights of displays include light conducting sheets into which light is coupled from linear light sources (such as CCFL tubes) placed along one or more edges. For increasing the overall energy efficiency of backlight, there is a need for efficient optical coupling between sheet and linear light source. There is a need for thin backlights for reducing the size of displays.
Linear light guides carrying light are used in illumination applications and communication applications. There is a need for efficient optical coupling between linear light guide (such as optical fiber) and point light source (such as LED or LASER). In the present art focusing lenses are used to couple light sources to optical fibers.